The present invention relates to an opto-electronic correlator, and particularly to an opto-electronic correlator with a large time-bandwidth product. Previously known correlators or so-called optimum filters or SAW filters (compare DE 32 48 539 C2) have relatively low time-bandwidth products. The ability to detect signals from noise is determined from the quotient of signal energy (power.times.time) and spectral interference power density; the ability to extract information, such as propagation delay, is determined from the time-bandwidth product of a signal.